This is a Test: Asteroid Tracking Network Observes Close Approach

This animation depicts the flyby of small asteroid 2012 TC4 as it passes under Earth. On Oct. 12 EDT (Oct. 11 PDT), 2012 TC4 will safely pass by Earth at a distance of approximately 26,000 miles (42,000 kilometers). Image credit: NASA/JPL-Caltech› Larger view

On Oct. 12 EDT
(Oct. 11 PDT), a small asteroid designated 2012 TC4 will safely pass by Earth
at a distance of approximately 26,000 miles (42,000 kilometers). This is a
little over one tenth the distance to the Moon and just above the orbital
altitude of communications satellites. This encounter with TC4 is being used by
asteroid trackers around the world to test their ability to operate as a coordinated
international asteroid warning network.

2012 TC4 is
estimated to be 50 to 100 feet (15 to 30 meters) in size. Orbit prediction experts
say the asteroid poses no risk of impact with Earth. Nonetheless, its close
approach to Earth is an opportunity to test the ability of a growing global
observing network to communicate and coordinate its optical and radar
observations in a real scenario.

This asteroid
was discovered by the Panoramic Survey Telescope and Rapid Response
System (Pan-STARRS) in
Hawaii in 2012. Pan-STARRS conducts a near-Earth object (NEO) survey funded by
NASA's NEO Observations Program, a key element of NASA's Planetary Defense
Coordination Office. However, 2012 TC4 traveled out of the range of
asteroid-tracking telescopes shortly after it was discovered.

Based on the
observations they were able to make in 2012, asteroid trackers predicted that
it should come back into view in the fall of 2017. Observers with the European
Space Agency and the European Southern Observatory were the first to recapture
2012 TC4, in late July 2017, using one of their large 8-meter aperture
telescopes.Since then, observers around
the world have been tracking the object as it approaches Earth and reporting
their observations to the Minor Planet Center.

This "test" of
what has become a global asteroid-impact early-warning system is a volunteer
project, conceived and organized by NASA-funded asteroid observers and supported
by the NASA Planetary Defense Coordination Office (PDCO).

As explained by Michael Kelley, program
scientist and NASA PDCO lead for the TC4 observation campaign, "Asteroid
trackers are using this flyby to test the worldwide asteroid detection and
tracking network, assessing our capability to work together in response to
finding a potential real asteroid-impact threat."

No asteroid currently known is predicted
to impact Earth for the next 100 years.

Asteroid
TC4's closest approach to Earth will be over Antarctica at 1:42 AM EDT on Oct.
12 (10:42 p.m. PDT on Oct. 11). Tens of professionally run telescopes across
the globe will be making ground-based observations in wavelengths from visible
to near-infrared to radar. Amateur astronomers may contribute more
observations, but the asteroid will be very difficult for backyard astronomers
to see, as current estimates are that it will reach a visual magnitude of only about 17 at its brightest,
and it will be moving very fast across the sky.

Many of the
observers who are participating in this exercise are funded by NASA's NEO
Observations Program, but observers supported by other countries' space
agencies and space institutions around the world are now involved in the
campaign.

Vishnu Reddy, an assistant professor at
the University of Arizona's Lunar and Planetary Laboratory in Tucson, is
leading the 2012 TC4 campaign. Reddy is principal investigator for a
NASA-funded near-Earth asteroid characterization project. "This campaign
is a team effort that involves more than a dozen observatories, universities
and labs around the globe so we can collectively learn the strengths and
limitations of our near-Earth object observation capabilities," he said.
"This effort will exercise the entire system, to include the initial and
follow-up observations, precise orbit determination, and international
communications."

In
September, asteroid observers were able to conduct a "pre-test" of coordinated
tracking of the close approach of a much larger asteroid known as 3122
Florence. Florence, one of the largest known NEOs, at 2.8 miles (4.5 kilometers)
in size, passed by Earth on Sept. 1 at 18 times the distance to the Moon.
Coordinated observations of this asteroid revealed, among other things, that Florence
has two moons.